1. Field of the Invention
This invention relates generally to devices for heating fuel oil prior to passage into a diesel engine. More particularly, this invention relates to a heater for heating diesel fuel within a fuel filter.
2. Description of the Prior Art
Diesel fuel, more particularly, No. 2 fuel oil has a tendency to jell or "wax" in cold weather. This jelling of diesel fuel is a particularly acute problem in the trucking industry in the winter months in the northern portion of the United States and throughout Canada. During the winter months, temperatures and windchill factors frequently reach minus 30 degrees fahrenheit or lower in these areas. In such a temperature and windchill range, diesel fuel tends to jell or wax both in the fuel tank itself and within the fuel line leading from the tank to the engine. In the severest incidence of jelling, the diesel engine completely fails. The truck must be towed to a service area. The towing and downtime of the truck results in increased transportation costs. In less severe instances, the jelling can result in loss of power so that the trucks are forced to travel at a slow rate of speed. This also results in increased transportation cost.
Numerous methods and apparatus have been used in the past in an attempt to solve this problem. Heating mechanisms have been interposed in the fuel supply line and in the fuel tank itself. In addition, devices have been used to heat a fuel filter and thereby the fuel oil in the fuel filter.
U.S. Pat. No. 3,935,901 issued Feb. 3, 1976, to Eldon E. Virgil is an example of a fuel filter heater. An arcuate chamber is fitted against a portion of a replaceable fuel line filter in a diesel engine. The chamber has inlet and outlet lines for passing engine exhaust gases through the chamber, thereby heating the fuel filter. The chamber does not surround the fuel filter, thus it directly heats only a portion of the fuel filter. In addition, the exhaust gases are separated from the fuel filter by an inner wall. The exhaust gases are not in direct contact with the fuel filter and the heat of the exhaust gases must pass through the inner wall before reaching the fuel filter.
In addition to heating the fuel filter to prevent jelling of the diesel fuel, it is also known to heat the fuel filter to remove gases contained in the fuel. U.S. Pat. No. 1,623,074 issued to E.H. Tartrais on Apr. 5, 1927 illustrates such a heater. A water jacket, having an inlet pipe and outlet pipe which allows circulation of the engine waters through the jacket, surrounds the fuel filter. However, the water jacket is spaced from the fuel filter and the water does not contact the filter. Therefore, the heat transfer is not optimal.
An example of a heated gas line vapor filter and internal combustion engine is shown in U.S. Pat. No. 4,003,356 issued Jan. 18, 1977 to Harry E. Naylor. A heating jacket having liquid lines to and from the radiator conveys fluid adjacent the fuel filter. However, the fuel filter is enclosed in the heating jacket and is not easily removable.